Pistol packing … Shrimp?!

Watch out for this little guy!

Published: 17 April 2012(GMT+10)

illustrated by Caleb Salisbury

Do you like shrimp for dinner? Well don’t mess with this pistol packing hombre!
Despite being a diminutive 1–2 inches (3–5 cm) long, the pistol shrimp
normally has one regular claw but also has an oversized claw which operates as an
acoustic weapon capable of producing ‘gunshots’ reaching over 200 decibels
(much louder than a jet engine!).

The violent implosion of this cavitation bubble produces the sound, the pressure
of which is strong enough to kill small fish.

Unwary victims approaching within an inch or so (~4 cm) of this oceanic ‘bush-whacker’
may find themselves staring down the barrel of a gun that is literally cocked and
triggered in a fashion reminiscent of a Wild West six-shooter.

Reach for the sky!

The sound the shrimp makes is not produced by its claws snapping together but by
a bubble formed by a fast water jet (travelling at speeds of up to 60 miles/100
kilometres an hour) squeezed out from a socket in the claw when it snaps shut (this
generates a low-pressure bubble).

The violent implosion of this cavitation bubble
produces the sound blast, the pressure of which is strong enough to kill small fish.
(This is similar to the pistol shrimp’s larger cousin, the 4–6 inch-long
(6–10 cm) mantis shrimp’s use of cavitation
to boost its ‘super powered’ punches). Researchers using high-speed
cameras and sound equipment say this whole process occurs within 300 microseconds
from when the shrimp ‘pulls the trigger’. The implosion also briefly
generates a temperature as high as the sun’s surface.

The shallow ocean gang

Not only are these shrimp armed and dangerous, they are also a rowdy bunch (“
… the shrimps’ snapping is the dominant source of background noise
in the shallow ocean”1).
They can easily compete with 40 ton heavyweights like whales in terms of ability
to create noise. In colonies they can interfere with submarine sonar; “When
colonies of the shrimp snap their claws, the cacophony is so intense submarines
can take advantage of it to hide from sonar.”2 (This problem was first discovered in WW II because
these creatures made it hard to detect hostile submarines!) Not only are the ‘gunshots’
used to attack, they are apparently used for communication as well.

Don’t mess with this pistol packing shrimp!

Cover me boys!

Several species of goby fish don’t fear this creature. The shrimp even rests
its antennae on the goby’s tail and body. Both sides benefit from this symbiotic
relationship. The shrimp can’t see well, so any sudden movement by the goby
signals the shrimp that it’s time to hide in its burrow. In return, the goby
is allowed to share this burrow for a safe home.3Symbiosis can be yet another conundrum for evolution.

Now on the other hand …

Unlike their gun-toting cowboy counterparts, pistol shrimps are notoriously hard
to disarm. Another clever trick up their sleeve is their ability to literally ‘switch
hands’. Laboratory research has shown that if something chops off the shrimps
‘pistol’ hand, the missing limb will regenerate into a regular smaller
claw and the original normal appendage will grow into a new snapping claw (severing
the nerve of the snapping claw induces the conversion of the smaller limb into a
second snapping claw). Some shrimp even have two pistol claws.4

Design demands a designer?

How could the building of a sonic gun, along with the biochemical and neural pathways
that would need to be integrated into the creature’s central nervous system
in a step by step process possibly happen?

Many people, astounded at the obvious design in such a creature, might ask, “How
could features such as the building of a sonic gun (along with the biochemical and
neural pathways that would need to be integrated into the creature’s central
nervous system) just happen by mutations and natural selection?” But an informed
evolutionist might easily counter this appeal to design in this way:

“All shrimp have claws already with neural pathways for control of closing
of the claw to catch prey (and quite quickly). Some might even discover that suddenly
closing their claw to jet water at small prey at close quarters, but just out of
reach, disorients them sufficiently for the shrimp to catch them. This process could
have been refined by slight changes to the claw over a period of time (via mutations),
developing more and more effective jets, culminating in ones with a sonic boom,
as in this species. The sonic boom is just the end result of the modification of
existing structures.”

(Please note that the purpose of the following critique is not to set up a straw
man argument against evolution. The argument used [above] is hypothetical, but typical
of how evolutionists have argued against ‘design’ in the past. This
exercise is to show how these particular points could be argued against.)

Call their bluff

This might stump some, or convince them that evolutionary concepts are credible.
But close examination reveals holes in such an argument. First of all, the use of
terminology like “ … some might even … ”, “ …
could have been … ” (commonly seen in evolutionary literature) highlights
the fact that these kinds of arguments are imaginings, not observed facts or even
extrapolations based on fossil evidence of transitional forms, etc.

Neo-Darwinian evolution says that tiny changes in living things that are useful
to the organism (providing some kind of survival benefit) are retained. This means
a bunch of smaller changes can result in big changes (like a leg into a claw or
a claw into a ‘sonic gun’). However, evolutionist Richard Dawkins admits:

“There cannot have been intermediate stages which were not beneficial. There’s
no room in natural selection for the sort of … foresight argument, that says:
‘Well we’ve got to let it persist for the next million years and it’ll
start becoming useful’ … That doesn’t work. There’s got
to be a selection pressure all the way.”5

The pistol shrimp’s claw is an extremely specialized construct that needs
precision design in order to function. Of the millions of random mutations that
might occur that would change the shape of a claw (a bump, indentation or protrusion
of some sort?) there would be precious few that would have been ‘on the way’
to becoming a ‘sonic gun’ variant. Granting that evolutionists admit
that beneficial mutations are rare, the point is; “What survival benefit would
those small shape changes have conferred to the shrimp on the way to becoming a
sonic claw?”

A similar comparison would be scales turning into feathers. As the scale changed
slightly, becoming something like a small bump or pimple, one has to wonder what
advantage that might give a lizard (on its way to becoming a bird). Dawkins actually
discussed this in an interview with TV show host Jonathan Miller:

JM: “What was it about that early novelty, before it culminated in something
as useful as a feather? Where could natural selection get its purchase upon something
which was no more than a pimple?”

RD: “ … there’s got to be a series of advantages all the way
in the feather. If you can’t think of one, then that’s your problem,
not natural selection’s problem. Natural selection, well, I suppose that is
a sort of matter of faith on my part since the theory is so coherent and so, and
so powerful.”6

So Dawkins’ belief is based on faith, not fact, just like the hypothetical
argument above.

Pistol shrimp and goby in symbiotic relationship

Tall Tales

One also has to wonder why shooting bubbles (at lesser speeds than those that which
can cause implosive cavitation bubbles) would ‘disorient’ a fish long
enough to allow a shrimp to catch it. Surely a sudden jet of bubbles of any velocity
would most likely frighten prey, thus prompt them to flee away from them,
not closer. The only reason a pistol shrimp can eat a meal he’s shot with
his gun is because it is stunned or dead!

Also, as the claw supposedly begins changing from an efficient grabbing tool into
a ‘gun’, its efficiency as a grabbing tool is surely going to be diminished.
Natural selection would work against such a change to eliminate it, unless the efficiency
of the claw as a gun were sufficient to make up for this. Creating a few bubbles
would hardly suffice to enhance survival enough to make up for the loss of grabbing
efficiency.

There is no present-day example (or in the fossil record) known of a shrimp or crab
with some kind of intermediate claw that disorients fish by shooting bubbles at
lesser speeds. There would be a threshold for the speed of snapping shut and the
volume of water displaced for the mechanism to make any difference at all. Natural
selection could not work on further improving this mechanism until this threshold
was reached. As Dawkins admitted, natural selection could not foresee an amazing
mechanism that would be achieved in the future.

According to Dawkins, “Biology is the study of complicated things that give
the appearance of having been designed … ”7 (emphasis mine). The ‘design’ argument
has been a powerful instrument in the creationist’s apologetic ‘tool
kit’ for years and evolutionists have often tried to explain away examples
of design with ‘just so’ stories rather than observable evidence. But
just because evolutionists say that there is a way that evolutionary mechanisms
could have produced such and such doesn’t mean that it did or that such an
explanation is credible.

The evolutionists’ series of diagrams supposedly showing how an eye could
evolve is a case in point. Beneath the simplistic line-diagram scenario lies nightmarish
biochemical complexity. Even the humble ferment fly (Drosophila) has over
500 genes involved in eye development.8
Vertebrates have many thousands of genes. Even one of these genes is beyond mutations
and natural selection to ‘create’. Even a light-sensitive spot—the
evolutionists’ first stage—involves enzyme cascades that the evolutionary
story sidesteps to make the story seem plausible.

As Romans 1:20 says, the evidence that the creator God of the
Bible exists is clearly seen in His creation, from the largest of whales to the
tiny shrimp!

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Comments closed

A reader’s comment

Katrina E.,United States, 17 April 2012

Would the shrimp stun itself if the bubble didn't travel far enough before collapsing?

Calvin Smith responds

Hi Katrina, thanks for your email.

The bubble might have to be close enough to the brain of the victim in order to be effective. Because of the position of the shrimp's claw in relation to its head when firing and the direction it is being shot in, the shrimp's own brain would be shielded from the force of the collapsing bubble even if it was closer to the end of its claw.